GAS THERMAL OIL HEATER SELECTION
How to Select a 2–12 Million kcal/h Gas-Fired Thermal Oil Heater
Select a gas-fired thermal oil heater from process duty, supply and return temperatures, thermal-fluid limits, circulation flow, pressure drop and the complete expansion, pumping, control and heat-recovery system.
QUICK ANSWER
Convert the process duty, then protect flow and fluid temperature.
Capacity
1 million kcal/h equals approximately 1.163 MW. JIELI’s published YY(Q)L range covers 200–1200 ×10⁴ kcal/h, with rounded nominal ratings from 2.4 to 14 MW.
Temperature
Specify supply, return, startup and upset temperatures. Check both bulk-fluid and film-temperature limits with the selected heat-transfer fluid supplier.
Circulation
Calculate flow from heat duty, fluid heat capacity and temperature difference, then verify density, viscosity, coil velocity, system pressure drop and pump NPSH.
Do not size only from kcal/h: two plants with the same duty can require different heaters, pumps, pipe sizes and expansion volumes.
01 · HEAT DUTY
Separate steady production from startup and simultaneous peaks.
Calculate the heat required by every reactor, dryer, press, coating line or other process user. Record steady production duty, batch warm-up energy and time, heat loss, simultaneous operation and future expansion. Selecting the heater from a single production label can miss a short but critical startup peak—or create an oversized heater that spends too much time at low fire.
1 million kcal/h = approximately 1.163 MW = 3.97 MMBtu/h.
Use one conversion basis throughout the proposal. The model names in a manufacturer table may use rounded nominal capacities, so compare the stated kW, kcal/h and MMBtu/h rows rather than reverse-engineering a model from its code alone.
02 · TEMPERATURE AND FLUID
Bulk-fluid temperature is not the same as film temperature.
Specify the required supply and return temperatures at normal production, startup and upset conditions. Then select the thermal fluid from its operating-temperature range, low-temperature viscosity, oxidation stability, vapor pressure, compatibility and supplier guidance.
The fluid next to the heated coil wall can be hotter than the measured bulk outlet. Insufficient flow, fouling or excessive heat flux can raise this film temperature and accelerate degradation. Eastman’s thermal-fluid design guidance emphasizes matching heater capacity, temperature and fluid velocity and using adequate turbulent flow to avoid hot spots.
03 · CIRCULATION
Calculate flow from duty and ΔT, then verify the real hydraulic loop.
For preliminary liquid-phase sizing:
ṁ = Q ÷ (cp × ΔT)
Volume flow = mass flow ÷ density
Use fluid properties at the relevant temperature. The final pump point must include heater-coil pressure drop, process users, control valves, strainers, piping and elevation. Check cold-start viscosity, minimum coil flow, pump NPSH, parallel-pump arrangement and operation when some users close.
Use the thermal oil flow-rate and pipe-size calculation guide for a worked hydraulic example, then continue with the thermal oil circulation pump selection guide after the duty and temperature range are fixed.
04 · YY(Q)L PRELIMINARY RANGE
Match capacity to published flow and main-pipe data.
The following rows reproduce the key preliminary values published on JIELI’s gas / oil-fired thermal oil heater product page. Rated output, circulation flow and main pipe size are starting points; the actual system must be recalculated for the selected thermal fluid and project pressure drop. Buyers comparing Chinese model families can also use the YYW, YYL, YLW and YGL model guide.
| Model | Rated capacity | Nominal power | Circulation flow | Main pipe |
|---|---|---|---|---|
| YY(Q)L-200 | 200 ×10⁴ kcal/h | 2,400 kW | 160 m³/h | DN200 |
| YY(Q)L-240 | 240 ×10⁴ kcal/h | 2,800 kW | 200 m³/h | DN200 |
| YY(Q)L-300 | 300 ×10⁴ kcal/h | 3,500 kW | 200 m³/h | DN200 |
| YY(Q)L-350 | 350 ×10⁴ kcal/h | 4,100 kW | 250 m³/h | DN250 |
| YY(Q)L-400 | 400 ×10⁴ kcal/h | 4,600 kW | 250 m³/h | DN250 |
| YY(Q)L-500 | 500 ×10⁴ kcal/h | 6,000 kW | 300 m³/h | DN250 |
| YY(Q)L-600 | 600 ×10⁴ kcal/h | 7,000 kW | 400 m³/h | DN250 |
| YY(Q)L-700 | 700 ×10⁴ kcal/h | 8,200 kW | 400 m³/h | DN300 |
| YY(Q)L-800 | 800 ×10⁴ kcal/h | 9,300 kW | 500 m³/h | DN300 |
| YY(Q)L-900 | 900 ×10⁴ kcal/h | 10,500 kW | 500 m³/h | DN300 |
| YY(Q)L-1000 | 1000 ×10⁴ kcal/h | 12,000 kW | 500 m³/h | DN350 |
| YY(Q)L-1200 | 1200 ×10⁴ kcal/h | 14,000 kW | 600 m³/h | DN400 |
Published maximum working temperature is 320°C and rated working pressure is 1.0 MPa for this preliminary range. Final design conditions depend on the thermal fluid, system static head, pump pressure, code and project safety margin.
05 · COMPLETE LOOP
The heater is one component of the thermal-fluid system.
| System item | Selection question | Failure to avoid |
|---|---|---|
| Circulation pumps | Can the pumps maintain minimum heater flow at hot and cold conditions? | Low flow, cavitation or coil overheating |
| Expansion tank | Does volume cover the fluid density change with correct cold and hot levels? | Overflow, low suction head or air contact |
| Process users | How do valves and bypasses behave as users open and close? | Unstable system flow |
| Controls | Are low-flow, high-temperature, pressure and flame trips independent and testable? | Unsafe continued firing |
| Piping | Is expansion flexibility, venting, draining and leak management engineered? | Stress, trapped gas or fluid leakage |
Eastman’s liquid-phase system guidance places the expansion tank at the high point and connects it toward the circulating-pump suction; it also recommends sizing from the selected fluid’s density change rather than using one universal percentage. See our expansion tank sizing guide for the calculation workflow.
06 · GAS AND EFFICIENCY
State the gas basis and evaluate efficiency across the load range.
Record natural-gas composition, pressure range, LHV or HHV, reference volume, emissions limits and backup fuel. Burner turndown should follow the minimum sustained process duty, while fan selection must consider furnace pressure, duct loss, heat-recovery equipment and altitude.
For preliminary gas flow, divide useful heat duty by efficiency and gas heating value on the same LHV or HHV basis. Then evaluate startup, part load, standby, fouling and actual operating hours. Use the gas boiler and heater fuel-consumption guide for the calculation steps.
Data required for a 2–12 million kcal/h gas thermal oil heater proposal
- Process duty by user, warm-up time, simultaneous load and future allowance;
- Thermal-oil supply, return, startup and maximum upset temperatures;
- Selected fluid name, property data and bulk/film temperature limits;
- Total system volume, elevation, pressure drop and required circulation philosophy;
- Natural-gas pressure, composition, LHV/HHV and emissions limits;
- Site altitude, ambient range, plot plan and transport constraints;
- Expansion, storage, pumps, controls, heat recovery and documentation scope.
TECHNICAL REFERENCES
Primary fluid guidance and related engineering pages.
- Eastman Therminol — Heat-transfer system design resources
- Eastman Therminol — Liquid-phase heat-transfer system design guide
- JIELI — Complete thermal oil heater selection guide
- JIELI — Published YY(Q)L-200 to YY(Q)L-1200 preliminary range
Model data are preliminary and do not replace a project heat balance, fluid-property review, hydraulic calculation, code review or supplier-guaranteed performance.
FREQUENTLY ASKED QUESTIONS
Large gas-fired thermal oil heater FAQ
How many MW is 2 million kcal/h?
Using the physical conversion, 2 million kcal/h is approximately 2.326 MW. A manufacturer’s nominal model table may show rounded kW values, so use the published capacity rows consistently.
How is thermal-oil circulation flow calculated?
Divide useful heat duty by the product of thermal-fluid specific heat and the selected supply-return temperature difference to obtain mass flow, then divide by density for volume flow. Verify the result against coil velocity, pressure drop and cold-start viscosity.
Is 320°C suitable for every heat-transfer fluid?
No. The heater design condition and the selected fluid’s bulk and film temperature limits must both be checked. Fluid condition, flow, heat flux and upset protection also affect safe operation.
Why does a thermal oil system need an expansion tank?
The fluid changes volume with temperature. The expansion system must accommodate that change, provide a stable inventory and pump suction condition, support venting and limit unnecessary contact with air where required by the fluid supplier.
Can a hot oil boiler be selected only by kcal/h?
No. Temperature range, thermal-fluid properties, circulation, coil velocity, pressure drop, burner turndown, expansion volume, controls and site conditions are also required.
JIELI THERMAL ENGINEERING
Turn process duty into a complete thermal-fluid system specification.
Send the duty table, supply and return temperatures, fluid data, gas specification, system volume, site location and scope boundary. We can review the heater, pumps, expansion system, controls and heat recovery together.
Request a thermal oil heater selection